Engine mount

ABSTRACT

An improved and tight package vibration isolator assembly increases the strength of the mount structure without compromising the efficiency of the damping features. An exo-skeleton bracket design provides a rigid structural strength able to withstand extreme loads. The bracket also allows forces to bypass the fluid components of the damping assembly that are otherwise subject to potential passage of forces therethrough. The exo-skeleton bracket provides a stiff structure that substantially surrounds the damping assembly. Tuning of the assembly is also simplified through use of a travel limiter assembly, the cross-section of which may change in shape, or characteristics of a surrounding resilient sleeve selectively altered, to tune the damping characteristics of the damping assembly.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a vibration isolator assembly, such asan engine mount or hydromount assembly, that dampens vibrations betweenrelatively moving surfaces of a vehicle, such as between an engine, orpowertrain, and vehicle frame.

[0002] Engine mounts are generally well known in the industry andtypically employ a combination of elastomeric and/or hydraulic featuresthat provide effective vibration isolation. The performance of the mountis directly connected to the volume of rubber and the clearance aroundit. Both are required for optimal isolation and rough load powertrainhandling. The space constraints also must address the need for accesstool clearance and assembly process feasibility.

[0003] Moreover, there are various constraints imposed in thisenvironment. For example, space or packaging is a primary concern asdesigns are required to deliver the same performance in smallerdimensional constraints. High temperature exposure is anotherconstraint. For example, the mount design must be capable ofwithstanding an excursion temperature on the order of 175° C. Anotherconstraint relates to high load conditions, especially for truckapplications, where the mount must be capable of handling peak loads onthe order of 10 G. Still another constraint is the ability to provide amount that can be easily tuned and preferably one that uses many of thesame mount components, including a modular type of design that allowscomponents or a subassembly to be added or removed as an option,resulting in ease of manufacture in developing different stiffnesses andforce/displacement relationships as desired.

[0004] Tradeoffs between these constraints have tended to limit thevarious mount designs brought to the marketplace. For example, packagingspace tends to discourage use of a heavy metal bracket, or sophisticateddesign driven by the hydraulic technology; however, part durability mustbe carefully considered if a heavy metal bracket is not used. A tradeoffalso exists between developing the proper rubber geometry that providesthe desired stiffness and durable rubber deformed shape required for atypical truck mount load, and at the same time designing the fluidrelated components of the mount in order to establish the requisitefluid effect that produces the high level of damping needed in, forexample, truck applications.

[0005] U.S. Pat. No. 6,499,729 provides a concise discussion of ways inwhich the industry has addressed the need for a stiffer sealing/crimpingarea. These current applications are loading through the crimp region orcrimp area of the mount, that is, the mount is directly supported ormounted through the cover. Since the cover is intended to carry theload, an increased emphasis is required on the sealing or crimping areain order to maintain a hydraulic or fluid-tight seal between the chamberand a reservoir. Thus, attention is directed to enhancing the perimeteror edge portion of the seal where the load transfer through the mountcover interfaces with the diaphragm/bellows arrangement.

[0006] It is also desirable to maximize the length of the track path onthe inertia track of a hydromount. Maximizing the track path lengthprovides sufficient fluid effect to produce a high level of dampingrequired in extreme load conditions such as encountered with a truckapplication. The inertia space and the need for high fluid damping havenot been adequately addressed in the prior art.

[0007] Because of the need to transfer forces or extreme loads throughthe mount, use of alternative materials of construction has beenlimited. Extreme loads typically require the mount structure to be atleast partially, if not entirely, formed of metal to withstand extremeloads. For example, typical hydromounts use the inertia track as atravel limiter or a structural reinforcement in order to stop powertrainmotion in compression and likewise reach higher modal frequencies.Therefore, it is conventional to form the inertia track from metal.

[0008] Still another problem encountered with prior arrangements is thatthe mount is usually secured to a vehicle flange along a large planararea. It has been determined that the planar interface is anotherpotential area of rattling or secondary resonation.

SUMMARY OF INVENTION

[0009] Improved isolation and improved powertrain handling/restrictionin rough road conditions are provided with the vibration isolatorassembly or mount of the present invention. The assembly meetsrestricted packaging space constraints and extreme load conditions whileproviding high mode frequencies.

[0010] An exemplary embodiment of the invention includes a structuralexo-skeleton bracket secured to one of associated first and secondsurfaces of a vehicle. A damping assembly is received in theexo-skeleton and thereby protected from transferred loads or forces bythe exo-skeleton bracket.

[0011] The damping assembly preferably includes an elastic wall having amajor portion thereof received in the exo-skeleton.

[0012] The bracket supports a travel limiter. The bracket isstrengthened at selected regions to support the travel limiter and thebracket configured so that a continuous surface extends from the supportregions to the first or second surface of the vehicle.

[0013] The travel limiter includes a resilient portion that tunes theforce versus displacement ratio of the vibration isolator assembly.

[0014] The damping assembly includes a fluid subassembly having aninertia track, a diaphragm, and a cover plate that divides thesubassembly into first and second sub-chambers.

[0015] The inertia track has a channel extending through a circuitouspath that reverses through approximately 180° multiple times betweenopposite ends of the channel.

[0016] A punctual contact is formed in a shell of the fluid mount toprovide abutting engagement with one of the associated first and secondsurfaces and limit vibration between the mount and the surface.

[0017] A primary benefit of the invention resides in the increasedstructural strength necessary to handle extreme loads and insure highmode frequencies.

[0018] Another benefit of the invention resides in the effectivevibration damping in a restricted packaging space.

[0019] Yet another benefit is realized by the transmission of forcesaround or outside of the mount subassembly.

[0020] Still other benefits and advantages of the invention will becomeapparent to one skilled in the art upon reading and understanding thefollowing detailed description.

BRIEF DESCRIPTION OF DRAWINGS

[0021]FIG. 1 is a longitudinal cross-section of a vibration isolatorassembly or engine mount formed in accordance with the present inventionmounted in a vehicle.

[0022]FIG. 2 is a perspective view of the assembly of FIG. 1 with thetravel limiter shown in disassembled relation.

[0023]FIG. 3 is an exploded, perspective view of the engine mountcomprised of the bracket assembly and the damping assembly.

[0024]FIG. 4 is perspective view of the bracket disassembled into firstand second bracket portions.

[0025]FIG. 5 is an elevational view of the assembled bracket.

[0026]FIG. 6 is a cross-sectional view taken generally along lines 6-6of FIG. 5.

[0027]FIG. 7 is an exploded perspective view of the damping assembly.

[0028]FIG. 8 is an elevational view of the assembled hydromount of FIG.7.

[0029]FIG. 9 is a longitudinal cross-section of the assembly of FIG. 8.

[0030]FIG. 10 is a cross-sectional view taken generally along lines10-10 of FIG. 9.

[0031]FIG. 11 is an exploded, perspective view of a fluid subassembly.

[0032]FIG. 12 is an elevational view of the assembled hydromountsubassembly of FIG. 11.

[0033]FIG. 13 is a top plan view of the subassembly of FIG. 12.

[0034]FIG. 14 is a bottom plan view of the subassembly of FIG. 12.

[0035]FIG. 15 is a cross-sectional view taken generally along lines15-15 of FIG. 12.

[0036]FIG. 16 is an enlarged detail view of the inertia track.

[0037]FIG. 17 is an enlarged detail view of the metal-to-metal path/lockthat seals the outer lower shelf or armature to the diaphragm/bellowsand upper shell/cover.

[0038]FIG. 18 is an elevational view of the assembled vibration isolatorassembly.

[0039]FIG. 19 is a top plan view of the assembly of FIG. 18.

[0040]FIG. 20 is a longitudinal cross-section taken generally alonglines 20-20 of FIG. 19.

[0041]FIG. 21 is a cross-sectional view taken generally along the lines21-21 of FIG. 20.

DETAILED DESCRIPTION OF THE INVENTION

[0042] Turning first to FIG. 1, first and second surfaces 30, 32 of avehicle (such as a truck) are shown in spaced relation with a vibrationdamper assembly, hydromount assembly, or engine mount 40 interposedbetween the associated surfaces that are adapted for movement relativeto one another. More particularly, the vibration isolator assembly 40 bydesign includes two major portions in accordance with the presentinvention. The assembly is divided into a first group G1 comprised offeatures needed to produce the required rates, including all of thetunable features used to obtain damping characteristics. A second groupG2 is composed of structural strength features needed to withstandextreme loads, including frame interface features.

[0043] More particularly, and with additional reference to FIGS. 2 and3, the damping assembly GI includes a travel limiter having an elongatedpin 42 with a generally rectangular cross-section (typically a roundcross-section in prior art arrangements) and an elastic sleeve 44received therearound. The tuning and damping structure and functions ofthe pin and sleeve assembly, i.e., the travel limiter, will be describedin greater detail below. The structural strength features of the dampingassembly are primarily provided by a bracket 46 that is assembled, e.g.,welded, from first and second bracket portions 48, 50, as a unitaryassembly. The bracket defines an exo-skeleton or peripheral structuralframe particularly useful in carrying the load conditions. The firstbracket portion 48 defines approximately one-half of the peripheral,elliptical shape of the bracket. It includes a curved wall portion 52dimensioned for metal-to-metal engagement with selected portions of thetuning/damping portion G1 of the assembly as will be described below. Inplan view, the first bracket portion defines a generally U- or C-shapedconformation in which the extended height of the curved wall portion 52receives a major portion of the damping assembly. First and secondtravel limiter support portions or tabs 54 are provided at terminal endsof the curved wall portion (also see FIGS. 4-6). Each support portion 54includes an elongated opening 56 that receives a limited axial length ofthe travel limiter pin 42 therethrough.

[0044] The second bracket portion 50 also includes a curved wall portion62 having an axial height that mates with the curved wall portion 52 ofthe first bracket portion and also receives a major portion of thedamping assembly therein. The curved wall portion 62 similarly includestravel limiter support portions or tabs 64, preferably at terminal,upper ends of the second bracket portion. Like the travel limitersupport portions 54 on the first bracket portion, these mounting tabsinclude openings 66 in the second bracket portion that also receive alimited axial extent of the travel limiter and resilient sleeve. Thus,as will be appreciated from FIGS. 4 and 5, when the first and secondbracket portions 48, 50 are secured together, such as by welding alongseam 68, the support portions and particularly the openings 56, 66thereof are aligned in mating arrangement for receipt of the travellimiter pin and resilient sleeve (FIG. 2).

[0045] The bracket is mounted to one of the first and second associatedsurfaces of the vehicle. More particularly, a means for securing ormounting 70 the bracket to the associated second surface is defined byangled flange portions 72 a-72 c integrally formed with and extendingfrom the curved wall portion 62. Each flange portion 72a-72c includes arespective mounting opening 74 a-74 c. The mounting openings are locatedfor mating engagement with respective mounting openings in theassociated surface 32 of the vehicle as represented by opening 76 (FIG.1). As will be appreciated, the spaced locations of the mounting holes74 a-74 c, particularly where opening 74 b is in a different plane fromthe remaining two mounting openings, provides a secure interconnectionwith the surface of the vehicle. Likewise, the individual flangeportions 72 a-72 c are non-planar so as to match and provide optimizedstability to the mounting arrangement with the surface of the vehicle.

[0046] As perhaps best illustrated in FIGS. 4 AND 5, the bracketportions 48, 50 are brought into mating engagement and secured togetheralong the seam 68. This provides a unitary metal bracket capable oftransferring high loads from the first surface to the second surface ofthe vehicle. The bracket is secured to one of these surfaces and, aswill become evident from the following description, the damping assemblyis secured to the other of these surfaces. As represented in FIG. 4,reference numerals 80 a, 80 b are representative of and illustrate acontinuous path of metal, i.e., it does not cross the weld, from thesupport tabs 64 to respective mounting openings 74 a, 74 b, 74 c. Thelocation of the weld seam does not compromise the material integrity ofthe metal in accordance with the stress/load going through the bracket.There are always continuous, single thickness metal paths to the mainstress/loads from the support tabs 64 to the mounting openings 74 a-74 cwithout having to pass through the weld seam. This provides a secure anddurable design required for heavy load conditions such as truckapplications.

[0047] Welding the first and second portions together provides aninexpensive way to manufacture the bracket. Thus, although its functionof providing the desired structural strength leads to a relativelycomplicated configuration, this particular design can be easilymanufactured. Moreover, the support portions 54, 64 provide a doublethickness of metal at the areas of high stress concentration. Theincreased thickness of metal accommodates a large amount of stress andthe continuous single thickness metal pads extending from the supporttabs assure that the load is effectively transferred to the mountingopenings. Consequently, the bracket design is unique in providing doublethickness metal at locations of high stress concentration, in providingmetal continuity from the support tabs to the frame attachment openings,and in providing overall bracket rigidity that provides high frequencyfor all modes (above 900 Hz).

[0048] With continued reference to FIGS. 1-6, and additional referenceto FIGS. 7-10, the damping assembly G1 will be described in greaterdetail. Particularly, an elastomeric body 90 which is typically anatural or synthetic rubber is molded to mounting member 92 such as analuminum structure. As is generally conventional, the mounting memberincludes first and second mounting means or studs 94. The studs aretypically externally threaded to cooperate with threaded members such asfastening nuts 96 (FIG. 1) that secure the damping assembly to the firstsurface 30 of the vehicle. The mounting member 92 has a recess 98 formedtherein and providing a generally U-shaped configuration as shown incross-section. The recess is adapted to receive the travel limiter pinand sleeve therein, with opposite ends of the travel limiter pin securedto the mounting tabs of the bracket.

[0049] A metal retainer 100 is received around and secured to the outerperiphery of the elastomeric body 90. A first end or upper edge of theretainer defines a metal flange 102 which cooperates with the bracket toform a portion of the structural strength feature G2 in conjunction withthe bracket. A second or lower end 104 of the retainer is scalloped orconfigured to form individual tabs 104 a that extend about the peripheryof the generally oval-shaped retainer for secure interconnection withthe lower shell 110. The lower shell is also generally oval-shaped anddefines a lower bowl or cavity that receives a hydromount subassembly SAtherein (FIG. 7). As will become more apparent below, the subassemblydivides an interior chamber in the elastomeric body into first andsecond chambers between which a fluid, such as a propylene glycolsolution or other similar fluid, is selectively transferred between thechambers to effect vibration damping.

[0050] More particular details of the subassembly SA are shown in FIG.11-16. It will be appreciated that the subassembly is shown in aninverted orientation in these figures relative to the orientation of theremaining figures, e.g. FIGS. 1-10. The subassembly includes an inertiatrack 120 having a double lap channel 122 that extends between a firstend or track entry 124 and a second end or track exit 126. The trackends are provided in the same orbit, that is, in the same internalorbital section of the channel. In addition, two 180° turns 132interconnect the internal orbital section of the channel with theexternal orbital section and thereby maximize the length of the channel.As fluid proceeds through the inertia track member via the entry 124, itproceeds leftward, then rightward as shown in FIG. 16 along the innerorbit of the channel before reaching the first 180° turn 132 a. Thefluid then transitions to the outer orbit of the channel and proceeds ina clockwise direction as illustrated. Before reaching the second 180°turn 132 b, the fluid traverses a substantial perimeter of the inertiatrack member. Proceeding through the second 180° turn 132 b brings thefluid back to the internal orbit. From there, it proceeds to the exit128 of the channel and communicates through side 130 of the inertiatrack member (FIG. 14).

[0051] A central cavity 140 is also provided in the inertia trackmember. The cavity communicates through multiple openings 142 in thesurface 130 with the chamber defined by the elastomeric body of thedamping assembly. A decoupler 144 is received in the cavity and heldtherein by cover plate 146. The cover plate also includes a series ofopenings 148 (opening 148 a is aligned with the entry 124 of thechannel) therethrough that communicate with the cavity 140 and with asubchamber 150 (FIG. 15) defined between the cover plate and bellows152. The bellows is preferably formed of an elastomeric material, suchas an EPDM, that includes an internal groove 154. The groove isdimensioned to clampingly engage outer perimeter portions of the coverplate when received in mating engagement with the inertia track.Shoulder 156 of the bellows holds the components of the subassemblytogether.

[0052] As illustrated in FIGS. 12 and 15, the subassembly defines adistinct, assembled unit dimensioned for receipt within the elastomericbody. As is generally known in the art, displacement of the elastomericbody in a downward direction (downward in relation to FIGS. 1, 9 and10), reduces the size of the chamber and urges fluid contained thereinthrough either the hydromount channel or through the cavity 140depending on the amplitude and frequency of the vibrations. If thedisplacement is relatively small in amplitude, the fluid flows withinthe cavity 140 and is responsive to small vibratory amplitudes at lowfrequencies. At a desired amplitude level, however, the fluid urges thedecoupler against the cover plate and thereby blocks communicationmovement within the cavity 140 and the fluid is forced through theelongated channel 122 to effect damping of the vibration.

[0053] The periphery of the subassembly is received between the lowershell 110 and the retainer 100. As particularly illustrated in FIG. 17,a robust fluid seal is thus provided among the lower shell 110, theperiphery of the bellows 152, and the retainer 100. As is perhaps bestappreciated from FIGS. 7 and 17, the lower plate 110 receives thesubassembly SA therein, and a perimeter collar 160 extends slightlyhigher than the height of shoulder 156 of the bellows. The tabs 104 aprovided at peripherally spaced locations around the lower end 104 ofthe retainer are then crimped to secure the subassembly in place anddivide the chamber of the elastomeric body 90. As shown in FIG. 17,metal-to-metal contact is thus achieved between the retainer 100 and thelower shell 110. Although the perimeter of the subassembly is heldbetween the retainer and the lower shell, substantially all of the loadcarrying capability is passed through the metal-to-metal contact andbypasses the subassembly. This provides a structurally stifferarrangement at the crimping area contributing to the overall mountingassembly stiffness. It also permits the inertia track to be formed of amaterial other than metal or the subassembly SA removed as an option, ifdesired, without compromising the assembly integrity. That is, theremainder of the damping assembly structural relationship is unaffectedif the subassembly is removed from the vibration isolator assembly.Typically, metal is used in prior arrangements because of the need tocarry some of the forces therethrough. As noted above, however, theexo-skeleton formed by the bracket and the metal-to-metal interface ofthe retainer and lower shell assure that the forces need not travelthrough the subassembly.

[0054]FIGS. 18-21 illustrate the insertion or assembly of the dampingassembly into the exo-skeleton bracket. Thus, as evident in FIGS. 18,20, and 21, substantially more than fifty percent (50%) of theelastomeric body 90 is received within the sidewall of the bracket. Thelower end 104 of the retainer is radially received within the innerperiphery of the bracket so that a metal-to-metal contact of theretainer within the bracket provides a press-fit relation that alsomaximizes stiffness. The radially extending flange 102 of the retainerabuttingly engages against the upper edge of the bracket. An upper shell160 is received over the damping assembly portion that extends outwardlyfrom the bracket. Opposite ends 162 a, 162 b of the upper shellabuttingly engage the first surface 30 of the vehicle and the radialshoulder 102 of the damping assembly. Thus, metal-to-metal contact isestablished from the first surface 30, the upper shell 160, the radialshoulder 102 of the damper assembly, the bracket, to the second surface32 of the vehicle.

[0055] Once seated therein, the travel limiter assembly is insertedtransversely through the aligned openings 56, 66 in the support tabs ofthe bracket. The travel limiter assembly passes through the recess 98 inthe damping assembly as illustrated in the FIGURES. Thus, the travellimiter assembly limits vertical upward movement of the elastomeric bodyand by virtue of the elastic sleeve 44, also provides support in otherdirections. Prior art arrangements use a travel limiter feature, but aretypically missing one of the vertical directions, either up or down.This resulted from the fact that the vertical stop is controlled in theprior art by internal contact between the core and the inertia track. Inthe present invention, the inertia track is not used as a vertical stopsince major stresses would otherwise be transmitted therethrough. Theinertia track is a sensitive component of the mount and any failure ofthe track can result in fluid leakage between the working andcompensation fluid chambers. Also, the sealing area of the mount can bedamaged and some fluid leakage could occur through the side of themount. With the present invention, however, the travel limiter assemblywith a removable sleeve allows the shape of the travel limiter to beselectively changed, e.g., circular or oval cross-section, for instance,and/or changing the rubber thickness and/or the hardness of the sleeve,allows the rate of the mount to be easily changed and adapted to avariety of applications while using substantially the same mount.Therefore, the mount rates, i.e., large displacement conditions, dependprimarily on the combined tuning of the travel limiter pin and therubber sleeve.

[0056] Still another feature of the present invention is found in theinterface between the lower shell 110 of the damping assembly and thesurface of the vehicle. As perhaps best illustrated in FIG. 1, themounting openings in the bracket are selectively aligned with theopenings in the first surface 32 of the vehicle. The lower shelltypically has an elongated inner face or surface area that mates withthe surface area on the vehicle. This is potentially prone tomisalignment, and potential rattling. Here, a local contact 164 isprovided through a lower surface of the shell. The local contactprovides a purposeful interrupt between the generally planar surfaces sothat the load is transferred through a controlled and well-definedsurface area.

[0057] In summary, the vibration isolator assembly satisfies thepackaging and load requirements by purposefully designing the dampingand structural features as different components and subsequentlyintegrating them together. The fluid mount is spared the heavy loadsencountered in prior art arrangements. The path of the track is alsounique. It is not simply a double track, but employs reverse curves intwo locations of the channel to maximize the length of the track.Contact between the bracket and the vehicle is also improved to providebetter noise vibration handling and reduce the prospects of secondaryresonation. Use of the exo-skeleton design allows the subassembly to beformed from different materials at a lower cost since the forces aretransmitted around the outside of the subassembly rather than throughit. Still another important advantage is the ability to tune thedeflection versus load characteristics of the mount by simply alteringthe travel limiter pin and/or sleeve. Merely changing the shape of thetravel limiter pin, or changing the rubber thickness or hardness of thesleeve, can very easily change the rate range of the hydromount undermore extreme conditions such as open throttle operation or abusive,off-road vehicle conditions without altering the elastomeric body andthe remainder of the structure. This provides a practical way to tunethe assembly as desired by a particular customer.

[0058] The invention has been described with reference to the preferredembodiment and method. Obviously, modifications and alterations willoccur to others upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations.

Having thus described the invention, it is now claimed:
 1. A vibrationisolator assembly interposed between associated first and secondsurfaces of a vehicle, the assembly comprising: a structuralexo-skeleton bracket dimensioned to extend between the associated firstand second surfaces for transferring forces therethrough, the bracketincluding means for securing the bracket to one of the associated firstand second surfaces; and a damping assembly received in the exo-skeletonthat is protected from the transferred forces by the exo-skeletonbracket, the damping assembly including means for securing the dampingassembly to the other of the associated first and second surfaces. 2.The vibration isolator assembly of claim 1 wherein the damping assemblyincludes an elastic wall portion and a shell forming a housing, theelastic wall portion having a major portion of its periphery received inthe exo-skeleton.
 3. The vibration isolator assembly of claim 2 whereinthe bracket includes first and second bracket portions each includingtravel limiter support portions that receive a travel limiter thereinthat limits travel of the elastic wall portion of the fluid mount. 4.The vibration isolator assembly of claim 3 wherein the travel limitersupport portions provide a double thickness wall at an attachment regionwith the travel limiter.
 5. The vibration isolator assembly of claim 2wherein the bracket includes first and second bracket portions, thefirst bracket portion having a continuous surface extending between thetravel limiter support portion and the first securing means.
 6. Thevibration isolator assembly of claim 5 wherein the first and secondbracket portions are joined along a seam offset from the continuoussurface.
 7. The vibration isolator assembly of claim 5 wherein the firstsecuring means includes spaced attachment points.
 8. The vibrationisolator assembly of claim 1 further comprising a travel limiterassembly that limits movement of the damping assembly, the travellimiter assembly including a resilient portion that tunes the forceversus displacement ratio of the vibration isolator assembly.
 9. Thevibration isolator assembly of claim 8 wherein the resilient portion isa rubber sleeve received over the travel limiter assembly.
 10. Thevibration isolator assembly of claim 1 wherein the damping assemblyincludes an elastic wall portion and a shell forming a housing, thehousing including first and second chambers divided by an elongatedchannel that permits selective communication between the first andsecond chambers.
 11. The vibration isolator assembly, of claim 1 whereinthe damping assembly further comprises a subassembly received in thechamber and separating first and second chamber portions, thesubassembly including an inertia track assembly including a housinghaving an elongated channel with first and second ends in fluidcommunication between first and second, opposed surfaces thereof,respectively, and at least one opening that is also in fluidcommunication between the first and second surfaces thereof, a diaphragmreceived adjacent the at least one opening of the inertia trackassembly, and an elastomeric member overlying the inertia trackassembly.
 12. The vibration isolator assembly of claim 11 wherein thesubassembly further comprises a cover plate received over the inertiatrack assembly having an opening extending therethrough in fluidcommunication with the first end of the inertia track channel, anddividing the subassembly into first and second subchambers.
 13. Thevibration isolator assembly of claim 12 wherein the cover plate furthercomprises at least one further opening that extends therethrough. 14.The vibration isolator assembly of claim 13 wherein the diaphragm isinterposed between the at least one opening in the inertia trackassembly and the cover plate.
 15. The vibration isolator assembly ofclaim 12 wherein the first subchamber is located between the elastomericmember and the cover plate.
 16. The vibration isolator assembly of claim15 wherein the second subchamber is located between the cover plate andthe inertia track.
 17. The vibration isolator assembly of claim 11wherein the first chamber portion is enclosed by a first elastomericwall member and the subassembly.
 18. The vibration isolator assembly ofclaim 11 wherein the channel has a circuitous path that includes firstand second 180° portions that interconnect inner and outer orbits of thechannel.
 19. The vibration isolator assembly of claim 11 wherein thesubassembly is selectively removable from the damping assembly withoutcompromising assembly integrity of the damping assembly.
 20. Thevibration isolator assembly of claim 1 wherein the damping assemblyincludes a fluid mount having an elastic wall portion and a shellforming a housing, the shell having a local contact that abuttinglyengages one of the associated first and second surfaces to limitvibration therebetween.